I think it would have to be house ruled. As far as I know the Ki Focus enchantment can only be added to melee weapons.

Bear in mind;

d20pfsrd wrote:

Magic Ammunition and Breakage: When a magic arrow, crossbow bolt, or sling bullet misses its target, there is a 50% chance it breaks or is otherwise rendered useless. A magic arrow, bolt, or bullet that successfully hits a target is automatically destroyed after it delivers its damage.

Shuriken is absent from this list - but it's ammunition none the less. I presume it follows these rules as well.

Shuriken is absent from this list - but it's ammunition none the less. I presume it follows these rules as well.

Equipment: "Although they are thrown weapons, shuriken are treated as ammunition for the purposes of drawing them, crafting masterwork or otherwise special versions of them, and what happens to them after they are thrown."